Newbie to this site, please be gentle and guide me if I'm doing it wrong.

On this puzzle, I got really stuck, and I think maybe there's a gap in the solution given.

(SPOILER ALERT)

In the solution (p. 67) it says, "If he [the prince with the 125-ft beard] were Prince Kenneth, the one with the 100-ft beard would be in Goatee Castle (clue 1)..."I don't understand why this is necessarily true. So far as I've gotten in the puzzle, if Kenneth were the 125-ft beard, according to clue 1, he could still be EITHER the prince rescued by Princess Shirley, OR the one whose beard was 25 feet longer than the prince in Goatee Castle.